Heparin-induced thrombosis without thrombocytopenia

Acute heparin-induced thrombocytopenia (HIT) without thrombocytopenia post aortocoronary bypass grafting

Heparin-induced thrombocytopenia (HIT) after cardiac surgery is a clinical condition associated with increased incidence of thromboembolic events and mortality. HIT without thrombocytopenia is a rare clinical entity poorly reported in the literature, especially after cardiac surgery. In this case report, we present the case of a post aortocoronary bypass grafting patient who presented with HIT in the absence of thrombocytopenia.

Heparin-induced thrombocytopenia in patients readmitted after open cardiac surgical procedures: A case series

Objectives

Heparin-induced thrombocytopenia (HIT) is an immune-mediated complication that occurs in a small percentage of patients exposed to heparin. Concerns of HIT are particularly high in patients undergoing cardiac procedures requiring cardiopulmonary bypass, as they are exposed to high doses of heparin intraoperatively. Our aim was to identify and assess the hospital courses of patients who were diagnosed with HIT during readmission following cardiac surgery.

Methods

A retrospective review of patients who underwent open cardiac surgical procedures from June 2017 through October 2019 was performed. Of these, we identified patients who were newly diagnosed with HIT upon readmission. HIT positivity was defined as a positive anti-PF4 antibody screening test, plus a positive serotonin release assay.

Results

Of the 2496 patients identified, 13 patients were HIT positive on index admission and were excluded. Of the remaining 2483 patients, 351 were readmitted within 30 days. Six were newly diagnosed with HIT during readmission, 5 of whom presented with thrombotic complications. One patient was readmitted with thrombocytopenia and was started on argatroban; the remaining 5 did not have a significantly lower platelet count on readmission. Of the 12 patients readmitted for venous thromboembolism, 4 tested positive for HIT.

Conclusions

HIT can have a delayed appearance following open heart surgery. Venous thromboembolism appears to be a significant indicator for HIT during readmission, even in the absence of thrombocytopenia. This may support the use of non-heparin anticoagulation for cardiac surgery patients readmitted with thromboembolism until HIT status is determined.

Production of Anti-platelet Factor 4/Heparin Complex Antibodies After Cardiovascular Surgery

To study the production of anti-platelet factor 4 (anti-PF4)/heparin complex antibodies of Ig (immunoglobulin) G/IgA/IgM using enzyme-linked immunosorbent assay (ELISA; heparin-induced thrombocytopenia [HIT] antibodies) in 79 patients undergoing cardiovascular surgery, we employed Δoptical density (OD) as a marker of HIT-antibody production. The ΔODs were calculated from the differences in the ODs using ELISA. Patient were classified into 3 ΔOD ranges: ΔOD ≥ 1.0, ΔOD ≥ 0.4 to <1.0, and ΔOD < 0.4. The underlying disease, time course of the postoperative platelet count, d-dimer level, postoperative brain magnetic resonance imaging (MRI), use of cardiopulmonary bypass and postoperative thrombocytosis were not considered for the 3 ΔOD classifications. None of the 6 patients with ΔOD ≥1.0 and a positive functional assay was diagnosed with HIT due to the absence of HIT-derived thrombocytopenia. In conclusion, HIT-antibody production increased until day 7 after heparin cessation and reached a trace level on day 14. It was demonstrated that HIT-antibody production is in remission unless there is any evidence of a further increase during the second week postsurgery.

The need for novel anticoagulation therapy in acute coronary syndrome

As acute coronary syndrome (ACS) becomes more common nationwide and current anticoagulation regimens used in patients with ACS continue to possess their shortcomings, the need for new anticoagulants is on the rise. Although heparin and warfarin are used effectively in patients with ACS, they both have significant side effects and delivery issues. New factor Xa inhibitors offer an oral alternative that functions early in the coagulation cascade. The role of these new drugs in ACS is explored here. Electronic search strategies were used to collect reviews, randomized controlled trials, and other studies. Databases used included Medline and Cochrane Library and hand selection. Sources selected were limited to those that discussed factor Xa inhibitors in the context of ACS. Selected studies were then assessed for quality and relevance and those deemed relevant included for analysis. Some of the factor Xa inhibitors such as rivaroxaban offer anticoagulation as effective as, if not more effective, heparin and warfarin with lower risks of bleeding and other adverse effects such as heparin-induced thrombocytopenia. Many of these new agents also come in oral form, making them easy for patients to manage and use daily.